On Mon, Apr 4, 2011 at 11:46 AM, Olin Lathrop w= rote: > Isaac Marino Bavaresco wrote: >> Perhaps because you may end applying power against the engine rotation >> and generate a knock. =A0There is a safe maximum advance limit. > > You can't have it both ways. =A0Either the combustion is delayed due to a= weak > spark or its not. =A0If it's delayed, then advancing timing to compensate > shouldn't cause knocking since the actual combustion still happens when y= ou > want it to. =A0If a weak spark doesn't delay combustion, then we're back = to > looking for a reason a stronger spark is necessary. > I am not an engine expert by any means, but could it not be true that a stronger spark decreases the duration of the combustion? In other words, there are actually two parameters: when the combustion starts AND how long it takes. Advancing/retarding the spark will only change the first of these two. Changing the spark energy might change the second one. Sean --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .